Upstream: fixed passwords support for dynamic certificates.

Passwords were not preserved in optimized SSL contexts, the bug had
appeared in d791b4aab (1.23.1), as in the following configuration:

    server {
        proxy_ssl_password_file password;
        proxy_ssl_certificate $ssl_server_name.crt;
        proxy_ssl_certificate_key $ssl_server_name.key;

        location /original/ {
            proxy_pass https://u1/;
        }

        location /optimized/ {
            proxy_pass https://u2/;
        }
    }

The fix is to always preserve passwords, by copying to the configuration
pool, if dynamic certificates are used.  This is done as part of merging
"ssl_passwords" configuration.

To minimize the number of copies, a preserved version is then used for
inheritance.  A notable exception is inheritance of preserved empty
passwords to the context with statically configured certificates:

    server {
        proxy_ssl_certificate $ssl_server_name.crt;
        proxy_ssl_certificate_key $ssl_server_name.key;

        location / {
            proxy_pass ...;

            proxy_ssl_certificate example.com.crt;
            proxy_ssl_certificate_key example.com.key;
        }
    }

In this case, an unmodified version (NULL) of empty passwords is set,
to allow reading them from the password prompt on nginx startup.

As an additional optimization, a preserved instance of inherited
configured passwords is set to the previous level, to inherit it
to other contexts:

    server {
        proxy_ssl_password_file password;

        location /1/ {
            proxy_pass https://u1/;
            proxy_ssl_certificate $ssl_server_name.crt;
            proxy_ssl_certificate_key $ssl_server_name.key;
        }

        location /2/ {
            proxy_pass https://u2/;
            proxy_ssl_certificate $ssl_server_name.crt;
            proxy_ssl_certificate_key $ssl_server_name.key;
        }
    }

1 files changed, 55 insertions, 0 deletions

diff --git a/src/http/ngx_http_upstream.c b/src/http/ngx_http_upstream.c
index 77dc032f2..d4cf1b7fe 100644
--- a/src/http/ngx_http_upstream.c
+++ b/src/http/ngx_http_upstream.c
@@ -6921,6 +6921,61 @@ ngx_http_upstream_hide_headers_hash(ngx_conf_t *cf,
 }
 
 
+#if (NGX_HTTP_SSL)
+
+ngx_int_t
+ngx_http_upstream_merge_ssl_passwords(ngx_conf_t *cf,
+    ngx_http_upstream_conf_t *conf, ngx_http_upstream_conf_t *prev)
+{
+    ngx_uint_t  preserve;
+
+    ngx_conf_merge_ptr_value(conf->ssl_passwords, prev->ssl_passwords, NULL);
+
+    if (conf->ssl_certificate == NULL
+        || conf->ssl_certificate->value.len == 0
+        || conf->ssl_certificate_key == NULL)
+    {
+        return NGX_OK;
+    }
+
+    if (conf->ssl_certificate->lengths == NULL
+        && conf->ssl_certificate_key->lengths == NULL)
+    {
+        if (conf->ssl_passwords && conf->ssl_passwords->pool == NULL) {
+            /* un-preserve empty password list */
+            conf->ssl_passwords = NULL;
+        }
+
+        return NGX_OK;
+    }
+
+    if (conf->ssl_passwords && conf->ssl_passwords->pool != cf->temp_pool) {
+        /* already preserved */
+        return NGX_OK;
+    }
+
+    preserve = (conf->ssl_passwords == prev->ssl_passwords) ? 1 : 0;
+
+    conf->ssl_passwords = ngx_ssl_preserve_passwords(cf, conf->ssl_passwords);
+    if (conf->ssl_passwords == NULL) {
+        return NGX_ERROR;
+    }
+
+    /*
+     * special handling to keep a preserved ssl_passwords copy
+     * in the previous configuration to inherit it to all children
+     */
+
+    if (preserve) {
+        prev->ssl_passwords = conf->ssl_passwords;
+    }
+
+    return NGX_OK;
+}
+
+#endif
+
+
 static void *
 ngx_http_upstream_create_main_conf(ngx_conf_t *cf)
 {